Here is Antonina's obituary:
Her son Valenty Proszogulowicz was buried in Limerick, Pennsylvania, so I'm assuming that she is in the same cemetery. His "Record of Burial Place of Veteran" card has "Limerick Garden of Memorial" but the actual name is Limerick Garden of Memories.
Here's the cemetery's web page:http://www.dignitymemorial.com/limerick-garden-of-memories/e...
They may be able to tell you who bought the plot and who else is buried there.